This invention relates to fuel dispensing nozzles of the type used to dispense gasoline for automobiles and the like, and more particularly, to an improvement to such nozzle assembly through which fuel which condenses in a vapor return hose of the nozzle assembly can be readily extracted and returned to the main fuel flow to allow clear vapor return to help reduce atmospheric pollution.
As is well known, gasoline dispensing nozzles of the type found in most service stations employ a spout which is inserted into the filler pipe of an automobile fuel tank. The size of the spout, and in particular, its diameter, is smaller than the diameter of the filler pipe. As a result, when the gas cap is removed from the filler pipe and the spout end of the nozzle is inserted there is typically substantial clearance between the side of the spout and the filler pipe. As a consequence, fuel vapors are allowed to escape from the tank into the atmosphere. Because of environment concerns, it is now a requirement in many locations that fuel dispensing nozzles be equipped so that this does not occur.
One way used to meet environmental requirements is to provide a nozzle with a flexible bellows assembly which fits over the spout. The bellows is circular in cross section with the diameter corresponding to the outer diameter of the filler pipe. When the nozzle is inserted into the pipe, the end of the bellows fits snuggly against the opening of the pipe so that the gasoline vapors escape into the bellows and are directed into a vapor recovery passage in the nozzle and eventually into the system for recovery. For example, see U.S. Pat. Nos. 4,031,930 and 4,016,910 which are assigned to the Husky Corporation, the same assignee as the present application. This is the balanced pressure type of vapor recovery.
Vapor recovery nozzles are provided in two types. One is vacuum assist, using a vacuum attraction created within the nozzle by means of a pump located back in the dispenser. This partial vacuum has a tendency to attract vapors back into the nozzle, through its hose, and back into the dispenser for collection.
A second system utilizes what is generally identified as the balanced pressure system, whereby the gasoline is pumped into the automobile fuel tank and the displaced air is forced back towards the nozzle, which forces the gasoline vapors to be captured through a bellows type boot for return back into the fuel line and, eventually, pushed back into the underground storage tank.
Examples of patents that disclose these types of systems, as previously reviewed, include the Walker U.S. Pat. No. 4,429,725, which shows the vacuum assist vapor recovery system; the Polson U.S. Pat. No. 4,351,375, which utilizes the direct force of the flow of dispensed fuel to regulate the opening or closing of a vapor recovery passageway, rather than the peripheral pressure generated by the fuel to obtain such; U.S. Pat. No. 4,232,715 which discloses the use of concentrically formed nozzle spout, including a vapor passageway, and which opens the vapor recovery valve through the actuation of a plunger when the fill pipe of the vehicle has the nozzle pressed against it when the nozzle is inserted for filling of the fuel tank. Other patents related to vacuum assists for removing vapors include the McGahey U.S. Pat. No. 4,223,706, and Lasiter U.S. Pat. No. 4,199,021.
U.S. Pat. No. 5,127,451 to Fink, Jr. et al. discloses a fuel dispensing nozzle improvement used with a vapor recovery hose attached between the nozzle and the fuel dispenser constructed as coaxial hoses, having an inner hose for the flow of fuel, and an outer hose, surrounding the inner hose, for the flow of vapors. The inner fuel flow hose cooperates with the outflow spout of the nozzle and the outer vapor recovery hose cooperates with a vapor flow pathway formed in the nozzle.
Fuel vapors occasionally condense in the vapor flow pathway in coaxial hoses and the condensed fuel needs to be drawn off or else the vapor return passage will be blocked, built up excessive pressure, and not work as intended. Furthermore, where a positive pressure is applied to the vapor flow pathway to draw vapors into the system, there is the problem with fuel being drawn into the vapor flow passage. The fuel will pool in the vapor flow pathway of the hose, especially if the hose has a depending loop when hanging on the pump.
Various attempts have been made to correct this problem, but there is still a need for an improved, simple, reliable and cost-effective solution. U.S. Pat. No. 4,687,033 to Furrow et al., discloses a evacuator system employing a venturi pump located in the hose to suck fuel back into the fuel flow line from the vapor flow path of the hose. In the Furrow invention, the venturi aspirator for removing accumulated fuel from the vapor path of the vapor recovery hose is included in the system between the nozzle and the meter housing. The venturi pump is located within the fuel flow path of the product hose for pumping out or aspirating liquid fuel that may accumulate in the vapor path of the vapor recovery hose.
U.S. Pat. No. 5,197,523, assigned to Husky Corporation, assignee of the present invention, employs a small bore extraction hose having one end which extends into the vapor recovery hose to a point where the condensed vapors will pool. The opposite end of the extraction hose is operatively associated with a venturi port located in the nozzle venturi which creates a positive pressure to draw the pooled fuel out of the vapor recovery hose, and direct it into the mainstream of fuel flow being dispensed. The disclosure of U.S. Pat. No. 5,197,523 is hereby incorporated by reference.
There are several problems associated with prior art vapor extraction devices. First, the vapor extraction devices are difficult or expensive to retrofit on existing fuel dispensing assemblies. If the extraction device is the type that is incorporated in the nozzle, it generally must be incorporated in the nozzle by the manufacture before fuel distribution. Furthermore, the small bore extraction tube extending from a venturi in the nozzle to the pooled fuel in the outer vapor flow coaxial hose has a tendency to get wrapped around the inner fuel flow hose, decreasing the efficiency of the system.